Directions:
Preheat oven to 375 degrees. In large mixing bowl, cream butter or margarine, sugar, egg yolk and vanilla until light and fluffy. Add flour, potato chips and chopped walnuts; mix well. Form into 1 1/2-inch balls and place 3 inches apart on ungreased cookie sheet. Grease the bottom of a glass that is about 3-inches in diameter.

Dip greased glass into sugar and use to flatten each ball. Place nut half into center of each cookie. Bake for 8 to 10 minutes. Cool slightly before removing from cookie sheet.